Proteins have a central role in all biological processes. The amino acid sequence determines the manner in which protein molecules can fold to form the secondary and tertiary structures important for biological function.
Sequence analysis of peptides and proteins may be accomplished by various known methods. Pursuant to one such method, described in U.S. Pat. No. 4,837,165, C-terminal sequencing is accomplished by reacting a peptide with an isothiocyanate having the chemical formula R.sub.(x) Si(NCS).sub.y where x=0-3, y may be 1-4 and R may be an alkyl c,r aryl substituent. A weak acid anhydride such as acetic anhydride may be mixed with the isothiocyanate. A tertiary amine such as pyridine may be included as a catalyst.
See also U.S. Pat. No. 5,049,507 which describes a C-terminal sequencing reagent comprising a mixed anhydride of isothiocyonic acid and a carboxylic, carbonic: or sulfonic acid.